In this case you are using a non-unique lookup criteria: phone number (together with your last name) and chances are that you have unintentionally (1) registered more than once with the same phone, (2) provided a wrong and/or dummy phone number OR (3) provided a phone number that was somebody else’s. Best way to address these challenges is by contacting customer service to make sure your profile is reflecting the most current information, including last name, email address and mobile phone number. Using My WU number or email address (together with your last name) is the most reliable way to check your balance and/or redeem rewards.